A recent paper by JA Heinemann, SZ Agapito-Tenfen and JA Carman (2013) “A comparative evaluation of the regulation of GM crops or products containing dsRNA and suggested improvements to risk assessments” presents a careful assessment of three regulatory regimes (Australia, New Zealand and Brazil) and their use of assumption-based reasoning to discount the risks of RNAi technology and the likelihood of harmful and unintended consequences. The authors discuss evidence from the scientific literature showing key assumptions made by these regulators are already known to be wrong. In addition, they provide case studies of previous regulatory failures, such as Vioxx and BSE, that stemmed directly from faulty assumption-based risk assessment. Heinemann et al. outline an alternative science-based risk assessment strategy for RNAi technology that takes into account known sequence-specific hazards and the current state of scientific knowledge.

6 Comments

Dear all.
Risk assessment is not meant to speculate on imaginary risks, but on those which have a clear, science-based route to harm. Heinemann´s recent paper has nice speculations on possible risks, but for risk assessors the suggestions are a mere exercise on curiosity.

admin
May 7, 2013 @
1:13 am

Dear Paulo Andrade,
It would help if you could be specific about what you think are the ‘imaginary risks’ raised by Heinemann. Off-target sequence specific risks and double stranded RNA risks are both very well supported by scientific experimentation and data. For example, see a very interesting paper on off-target effects in the model plant Arabidopsis: Xu et al. (2006) Computational Estimation and Experimental Verification of Off-Target Silencing during Posttranscriptional Gene Silencing in Plants, Plant Physiology Vol. 142:429-440. (http://www.plantphysiol.org/content/142/2/429.full). These authors found both off-target gene silencing for many predicted targets, as well as a mutant phenotype that appeared to be caused by the gene silencing, rather than lack of expression of the targeted silenced gene.

Hi Paulo
Regulators often frown on what they consider to be “imaginary risks”
This was just sent to me. The AEBC was the UK Agriculture and Environment Biotechnology Commission set up to examine public concerns about biotech. ACRE is the current UK GMO regulatory body:
“[AEBC]: Do you think people are reasonable to have concerns about possible ‘unknown unknowns’ where GM plants are concerned?
[ACRE Chair]: Which unknowns?
[AEBC]: That’s precisely the point. They aren’t possible to specify in advance. Possibly they could be surprises arising from unforeseen synergistic effects, or from unanticipated social interventions. All people have to go on is analogous experience with other technologies.…
[ACRE]: I’m afraid it’s impossible for me to respond unless you can give me a clear indication of the unknowns you are speaking about.
[AEBC]: In that case don’t you think you should add health warnings to the advice you’re giving ministers, indicating that there may be ‘unknown unknowns’ which you can’t address?
[ACRE]: No, as scientists, we have to be specific. We can’t proceed on the basis of imaginings from some fevered brow….”
[AEBC public meeting, London, 2001]
END
Paulo: AEBC was disbanded for its impertinence, the regulator is still in place. And that regulator has recently requested that (highly speculative) benefits should be part of its remit. Thus regulators (in my experience) hate speculation about hazards but are very comfortable with speculative benefits, like the reduced herbicide use that was promised to accompany GMOs but never happened.

admin
May 7, 2013 @
1:41 pm

Reply to Paulo Andrade received from Jack Heinemann:
The purpose of risk assessment is to ensure that safe biotechnologies are used to the benefit of society. A key contribution of our paper was that it reviewed the evidence for the faulty assumption that the genome of human cells could not be exposed to the effects of dsRNAs of plant origin, or other materials in our food. Since this assumption was decidedly incorrect, subsequent risk assessments failed to adequately require tests for potential adverse effects. All risk assessments are by definition speculative because their raison d’etre is to identify, eliminate or mitigate risk before a harm occurs. Waiting until a harm is caused is to fail as a risk assessor and to undermine society’s confidence in both the regulatory system and biotechnology in general.

In many countries it is the legislated obligation of the risk assessor to consider the risk. We catalogue a failure to do this because many assumed that there was no possibility of exposure, or because they arbitrarily determined all RNA to be safe. Dr. Andrade’s approach to risk assessment creates the possibility for real harm. One that most people believe they should not have to chance. Our approach to risk assessment, peer-reviewed to the highest international standard, provides sound scientific rationale for determining the safety of good products.

Dear readers.
A recent paper evaluates the number of potential plant dsRNA that could interfere with the expression of human genes via RNA mediated interference. More than 8 million potential ds RNAs were investigated from lettuce, tomato, soybean, rice and corn. The plant RNAs can potentially interfere with the expression of more than 30,000 human transcripts!

Bingo: praise Heinemann, Hilbeck and all those who alerted how dangerous dsRNA are and how inaccurate and precipitate all risk assessors were (including myself). But these are plain, regular dsRNAs from edible plants, eaten cooked, processed or raw by billions of people for thousands of years, without any report of toxicity due to their RNAs. And if plant dsRNA have so many potential targets in our transcriptome, imagine how many more beef, chicken or fish meat may have. Mankind is condemned to die of eating…

The current paper heralded by Dr. Andrade continues a pattern of
selective use of the literature to promote his belief that all dsRNAs
will be safe. Like the previous paper published by the same group, it
provides no evidence to exclude uptake of dsRNAs into consumers (animal
or human) or absence of effects from these naturally occurring dsRNAs.
What papers such as this do is provide a service to risk assessment
because they confirm the premise of most risk assessments, and that is
that the history of eating conventionally bred plants is a reasonable
premise for assuming their safety. What this research cannot do is
replace the need for focused case-by-case risk assessment on products of
genetic engineering because they do not have a history of safe use.

Dr. Andrade raises the familiar assumption-fueled argument that the
existence of dsRNAs in organisms we regard as safe makes the dsRNAs in
them safe and by extension all dsRNAs safe. As evidence he presents the
latest paper (Jensen et al) from the Monsanto group that isolates,
catalogues and then compares the potential regulatory RNA pool
(represented by the dsRNA pool) in plants used as food to the human
genome. This latest work adds to previous work by Ivashuta et al in 2009
to which one of us (JAH) responded in 2011 (Heinemann et al. Environment
International v37 p.1285–1293) and we both summarised in 2013
(Heinemann et al Environment International v55 p43-55). Note that the latter is open
access and available free to all readers.

Contrary to what Dr. Andrade implies, the idea that dsRNAs with the
potential to regulate genes in animals including humans was not a
construct that was unique to us. Ivashuta et al point to this risk as
inspiration for their 2009 paper when they say that: “the current
peer-reviewed literature lacks published studies specifically assessing
the safety of consuming endogenous longer dsRNAs, siRNAs or miRNAs in
human food or animal feed” and that they wanted to contribute to a
“documented history of safe consumption for small RNAs in order to
demonstrate the safety of the RNA molecules involved in this form of
gene suppression in plants” (p. 354). We wholeheartedly agree with this
ambition and contributed to this lofty goal by describing a thorough and
achievable risk assessment framework in our 2013 publication. We note
that researchers at the US Department of Agriculture have now published
a similar framework to ours because they too recognise the same
potential for harm: see Lundgren and Duan (2013) .

There is an important difference between Dr. Andrade’s assumption-based
framework–that relies on an absence of evidence that all dsRNAs in
existing food are safe and that all potential dsRNAs that might be
introduced through genetic engineering into food will be safe–and ours.
That key difference is that our framework does not make the same
unverified assumptions and calls for testing.

(1) The existence of dsRNAs in food plants with the potential to
interfere with human gene expression says nothing beyond verifying that
the plants we have eaten for a long time are safe. That does not mean
that every molecule in food would be found to be safe delivered any
other way or at any other concentration. We do not assume that new
dsRNAs created by genetic engineering, or existing dsRNAs expressed at
different levels because of genetic engineering, will necessarily be
benign or that animals and humans will be exposed to them in exactly the
same ways that they were exposed to the conventional versions of these
plants or other genetically engineered products. That is the purpose of
case-by-case risk assessment.

(2) As we’ve said before, the potential adverse effect being discussed
is “sequence-determined” and thus new dsRNAs created by genetic
engineering which by definition have novel sequences have no history of
safe use in the environment or in food. Plants that historically
produced potent toxic dsRNA molecules would likely have been screened
from the human diet thousands of years ago. That is why we advocate a
case-by-case risk assessment approach, compatible with Codex
Alimentarius and most environmental risk assessments, to exclude to an
acceptable standard the possibility of harm from novel dsRNA molecules.

(3) It is certain that novel dsRNA molecules transmit through food (and
by contact) to invertebrates and these molecules can cause harm to those
animals. We have given the example several times. dsRNA molecules of
novel sequence are being expressed in plants such as maize/corn. They
are designed to, and actually do, kill these animals. Thus it is proven
that these animals which have eaten corn for thousands of years and have
demonstrated no adverse effects from having done so can experience an
adverse effect when they eat corn with a novel dsRNA molecule.

(4) Will the same happen to mammals and humans? We don’t know, but there
is evidence that mammals and humans do take up at least some dsRNAs from
their food and that these molecules in mice can cause a change in gene
expression in the liver. There are varying degrees of confidence in
these results, but they stand far from being refuted. We discuss two
papers that provide such evidence in our 2013 paper and one of us (JAH)
has posted comments about a third here:http://www.sciencemediacentre.co.nz/2013/07/02/plants-in-our-diet-
unlikely-to-regulate-genes-study/. Also, the authors of one of the
studies has reflected on the same paper here: http://t.co/LxOy4XL4Xo.

(5) It can also not be said in advance that all future exposures to
novel dsRNAs will be dietary. For example, there is clear evidence that
inhalation exposure would be relevant to humans. Contact exposure may
also be. New pesticides based on a dsRNA active ingredient will
undoubtedly be made specifically to cause transfer of the dsRNA through
the skin.

Humans and animals eat grams of protein a day, yet it is obvious to most
that not all proteins are safe for everyone even if all proteins are
made from the same 20 amino acids. Similarly, it is a leap to anticipate
that all RNAs will be safe to everyone because they are all made from
the same 4 ribonucleotides. Sequence, structure, context and exposure
routes matter.